1. Field of the Invention
The invention relates to an apparatus for eliminating backlash in gear trains of printing machines.
2. Description of the Related Art
In spur gear trains, the backlash accumulates from gearwheel to gearwheel and this leads to an impermissibly large amount of backlash, especially in the case of long in-series gear trains, thus impairing operation.
European Reference EP 0 849 0478 discloses an apparatus for avoiding backlash between a first and a second gearwheel. For this purpose, an additional auxiliary gearwheel is arranged on the axis of rotation of a first gearwheel, being turned counter to the direction of rotation of the first gearwheel by a resilient force and thereby subjecting the engagement between two teeth of the second gearwheel to stress.
Auxiliary gearwheels that are arranged on the same shaft in a fixed manner but turned counter to the gearwheel are also generally known.
However, these solutions require such an auxiliary gear on every second gearwheel. This represents a large outlay on materials and assembly, especially in the case of longer gear trains. Moreover, there is always a minimum residual backlash, especially with fixed auxiliary gears.
The object of the present invention is to provide a simple apparatus in which the toothing rests in a defined manner on the load-bearing tooth flanks while minimizing costs related to materials and assembly.
According to the present invention, this object is achieved by providing a brake with an adjustable braking power on at least one shaft having a gear wheel. Due to the simplicity of the construction of the present invention, auxiliary gearwheels are no longer necessary thereby reducing the cost of materials and assembly.
By means of the present invention, an additional artificial adjustable load is introduced into a gear train, thereby creating clearly defined conditions for contact between the tooth flanks of intermeshing gearwheels.
One particular advantage of the present invention is the ability to adjust braking force or load during operation, allowing the apparatus to be adapted in an optimum manner to the requirements of the particular gear train. It is thus possible to drive precisely even assemblies with a low internal friction power, such as drives for transverse perforations. Advantageously, the accuracy of folding is improved due to the prevention of backlash in the gear train.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.